HP 8560A Service Manual page 235

582 AMPL
the correct rate. The error is detected in sweeping on the skirts of the
A properly operating sweep generator generates a series of
negative-going parabolas. These parabolas generate the sweeps used to
adjust resolution bandwidths of 10 kHz and below. Check the sweep
generator with the following steps. Refer also to "300 Hz to 3 kHz
Resolution Bandwidth Out of Specification" in the A4 Cal Oscillator
troubleshooting text in Chapter 8.
2. Connect an oscilloscope probe to A4U804C pin 8.
3. On the spectrum analyzer, press (CAL) and FULL IF ADJ .
583 RBW 30K Unable to adjust 30 kHz Resolution Bandwidth. SYSBW and LCBW
disagreement in LCCAL.
584 RBW IOOK Unable to adjust 100 kHz Resolution Bandwidth. SYSBW and LCBW
disagreement in LCCAL.
6-30 General Troubleshooting
Unable to adjust 100 kHz and 210 kHz Resolution Bandwidths. Bad
CALOSC Calibration in Sweep Rate. Test the 100 kHz Resolution
Bandwidth filter 3 dB bandwidth as follows:
1. Connect the CAL OUTPUT signal (A4J8) to the INPUT 50R.
2. Press (PRESET) and set the controls as follows:
CENTER FREQ . . . . . . . . . . . . . . . . . . . . . . . . . . .300 MHz
SPAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 500kHz
Resolution Bandwidth . . . . . . . . . . . . . . . . . . . . . . 100 kHz
LOG dB/DIV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 dB
REF LEVEL . . . . adjust to place signal peak at top of the screen
3. Press
and MARKER DELTA and turn the knob
( )
PEAK SEARCH
clockwise to position the marker until the delta MKR reads -3 dB
+ / - . l dB.
4. Press MARKER DELTA and move the marker to the other side of the
peak until the delta MKR reads 0 dB +/-.l dB.
5. If the delta MKR frequency is between 90 kHz and 110 kHz,
the 100 kHz Resolution Bandwidth is working properly. If the
frequency is outside these limits, read the following information on
the A4 Cal Oscillator sweep generator.
If the 100 kHz Resolution Bandwidth works properly, the A4 Cal
Oscillator sweep generator is failing to sweep its oscillator frequency at
100 kHz Resolution Bandwidth.
1. Remove the shields.
for negative-going parabolas (similar to half-sine waves) 5 ms wide
and approximately -4 V at their peak. Refer to Chapter 8, "IF
Section," for more information on the A4 Log Amp/Cal Oscillator
Assembly.